Potential of Eisenia foetida as a protein source for broiler chickens and its effect on growth performance, diggestive organs, and bone strentgh and meat characteristics

Abstract

This study was conducted to determine the nutrient composition of Eisenia foetida earthworm meal and its effects as a protein source on growth performance, carcass characteristics and meat quality of broilers. Protein content was higher in freeze-dried earthworm meal while drying methods did not influence fat content. Most minerals (macro and micro) of E. foetida meal were significantly different except for calcium (P < 0.05) with freeze-dried E. foetida meal having the predominant minerals than oven-dried earthworms. Most essential fatty acids were significantly higher in oven-dried E. foetida meal than in freeze-dried earthworm meal. A total of 180 day old Cobb broilers were randomly allocated to five dietary treatments as follows: T1 (0 percent), T2 (1 percent), T3 (3 percent), T4 (5 percent) and T5 (10 percent) earthworm meal inclusion. The FCR was significantly influenced by dietary treatments at 0-21d of age, with T1 birds had the best FCR than all dietary treatments. At 22-28 days of age, significant dietary effects (P < 0.05) were observed on ADG and ADFI. The highest ADG was recorded in T3 birds (89.9g), the least ADG was seen in T5 (60.9g). All growth traits were significantly different (P < 0.05) across dietary treatments at 29-35 days of age. Birds in T4 recorded the highest values of BWG (1137.9g) and ADG (162.5g) and the least BWG and ADG of 882.9g and 126.1g, respectively, were observed in T3 while, ADFI was highest in T3 birds (199.4g) and the least was recorded in T5 (164.4g). Furthermore, birds in T4 had the highest (1.6) FCR and birds in T1 recorded the least value (1.2). At 1- 35 days of age no significance difference (P > 0.05) was observed on ADG, ADFI, and FCR among different inclusion levels of E. foetida meal. The dietary effect was observed on BWG (P < 0.05) and birds fed 5 percent inclusion of earthworm meal (T4) had the highest body weight gain of 2590.4g. However, no significant difference (P > 0.05) was observed in the dressing percentage for birds fed with or without E. foetida meal. Birds in T3 had the highest (2.1kg) body weight, while the least body weight was recorded for birds in T5 (1.7 kg). Dietary treatments did not significantly (P > 0.05) influence gizzard pH. However, gizzard weight and intestine weight were significantly different (P < 0.05) among dietary treatments. Birds in T2 exhibited the highest gizzard weight (42.5g) and birds in T4 recorded the least weight of 36.1g. The highest intestine weight of 92.2g was observed in birds in T3, while the least weight of 80.1g was observed in birds in T5. Dietary treatments significantly influenced bone strength, where birds in T1, exhibited the highest strength and those in T2 exhibited the lowest bone strength. Bone ash percentage was influenced by dietary treatments. Birds in T2 had the highest ash percentage (70.2 percent) where those in T3 and T4 had the least bone ash percentage. Wing, thigh, and drumstick yield were significantly (P < 0.05) higher in T3 birds, whereas the breast yield was the highest in T5 birds. Liver and gizzard yield were significantly higher in birds in T5, while the least values were seen in birds in T3. Furthermore, there were no significant differences (P > 0.05) observed with heart and spleen yield among the birds fed different treatments. The highest values for L* and b* were found in T4 birds while the highest values for a* were found in T1 (control) birds. The pH values of breast meat were affected (P < 0.05) by the dietary treatments at 1 and 48 hours post-mortem. However, at one hour post-mortem, the highest pH values were observed in breast meat of birds in T3 (6.6) and T5 (6.6) while at 48 hour post-mortem, the highest values were seen in T1 (5.8) birds. Dietary treatments had a significant influence (P < 0.05) on cooking loss; even though, there were no differences (P > 0.05) observed on shear force values among the dietary treatments. The highest cooking loss value was observed in T5 (12.0 percent) and the lowest value in T3 (7.2). There were no significant differences (P > 0.05) on chicken aroma and metallic aroma scores of breast meat across the dietary treatments. Moreover, dietary effect (P < 0.05) was observed on first bite scores of breast meat; where meat from T2 had the least score of 2.6, while meat from T5 had the highest score of 3.5. However, breast meat from T5 was found to have the highest scores (3.9) for the initial juiciness and sustained juiciness (P < 0.05), while the lowest scores (2.5) were observed in T2. Chicken and metallic flavor scores of breast meat were not influenced (P > 0.05) by the dietary treatments, contrary to toughness scores (P < 0.05). Breast meat from T5 exhibited the highest scores (3.5) of toughness, whereas the least scores (2.3) were from birds in T2. It was, therefore, concluded in the current study that E. foetida can be considered as an alternative source of protein as it seems to be particularly suitable in broiler nutrition.